This socket fits sump plugs UG526 and RG3744.  These plugs are found on Dawn, Cloud, Shadow, Spirit/Spur oil sumps as well as Shadow final drives and fuel tanks - and probably a bunch of other stuff.
These sockets are milled to .525".  Having this socket allows you to keep your factory multi-tool where it belongs - in the tool kit.  This socket has a 1/2" drive.
If your UG526 sump plugs have already been vandalized, British Tool Works offers new ones under the "New Parts" tab.